Genetic Forms of Iron Deficiency
Anaemia
Photis Beris, MD
Professor of Clinical Haematology
Department of Internal Medicine
Geneva University Hospital
Geneva, Switzerland
Slide 1 of 21
Genetic Forms of Iron Deficiency Anaemia
• Mutations in the gene encoding DMT1
• Mutations in the gene encoding glutaredoxin 5
• Hypotransferrinaemia or atransferrinaemia
• Deficiency of ceruloplasmin
• IRIDA (Iron-Refractory, Iron-Deficiency
Anaemia)
Slide 2 of 21
Iron Deficiency Anaemia
Overview of Iron Homeostasis
With permission from Andrews NC. Blood. 2008;112:219-230.
Slide 3 of 21
Genes Involved in Hereditary Iron Deficiency
Anaemia
Protein (Gene
Symbol)
Chromosome
Protein Function
DMT1 (SLC11A2)1
121
Transmembrane iron
transporter1
Autosomal recessive hypochromic,
microcytic anaemia with hepatic iron
overload1
Glutaredoxin 5
(GLRX5)1
141
Participates in iron-sulfur
cluster biogenesis1
Anaemia with iron overload and
sideroblasts1
Transferrin (TF)1
31
Plasma iron binding
protein; ligand for TFR1 &
TFR21
Iron deficiency anaemia with tissue iron
overload1
Ceruloplasmin (CP)1
31
Plasma ferroxidase1
Mild iron deficiency anaemia associated
with iron accumulation in the liver and
brain1
Matriptase -2
(TMPRSS6)1
222
Regulates hepcidin
expression by an unknown
mechanism1
IRIDA1
With permission from Andrews NC. Blood. 2008;112:219-230.
1. Andrews NC. Blood. 2008;112:219-230.
2. Finberg KE, et al. Nat Genet. 2008;40:569-571.
Disease Caused by Mutations
Slide 4 of 21
Mutations in the Gene Encoding DMT1
Haematologic and Biologic Data of the 3 Described Families
with Microcytic Anaemia Secondary to DMT1 Mutations
French1
Czech2
Italian3
Age (years)
6
20
5
Hb (g/L)
75
74
85
MCV (fL)
53
54
51
MCHC (g/L)
287
296
295
Serum iron (µM/L)
28
43
36.5
Transferrin
saturation (%)
68
84
90
Ferritin µg/L
18
153
34
MCV = mean corpuscular volume; MCHC = mean corpuscular haemoglobin concentration.
1. Beaumont C, et al. Blood. 2006;107:4168-4170. 2. Priwitzerova M, et al. Blood. 2004;103:3991-3992.
3. Iolascon A, et al. Blood. 2006;107:349-354.
Slide 5 of 21
DMT1 Mutations Lead to Microcytic
Anaemia, Low (Normal) Ferritinaemia, and
Liver Iron Overload
Iron absorption in the duodenum continues
because the absorption of heme iron is not
disturbed. In fact, in meat-eating humans it is
estimated that about 2/3 of absorbed iron comes
from heme. Thus, in humans, a mutation in
DMT1 protein may primarily affect iron utilisation
and not absorption, leading to severe microcytic
iron deficiency anaemia with increased iron
stores.
Mims MP, et al. Blood. 2005;105:1337-1342.
Slide 6 of 21
Mutations in the Gene Encoding
Glutaredoxin 5
Non-erythroid cells
Case Report
44-year-old man
Hb 88.6g/L, MCV 59fL, TF% 52
Ferritin 1100 mg/L
BM: erythroid hyperplasia,
28% ringed sideroblasts
Erythroid cells
The patient had a
homozygous mutation that
interferes with intron 1
splicing and drastically
reduces glutaredoxin (GLRX5)
RNA
GLRX5 has an essential role
in the synthesis of Fe/S
clusters
DFO = desferrioxamine; hb = haemoglobin; MCV = mean corpuscular volume; BM = bone marrow; Fe/S = ironsulfur.
With permission from Camaschella C, et al. Blood. 2007;110:1353-1358.
Slide 7 of 21
Hypotransferrinaemia or Atransferrinaemia
Caucasian woman 20 years of age with:
• Hb 106 g/L; MCV 75.3 fL; iron serum 15 µg/dL; serum
total iron binding capacity 23 µg/dL; ferritin >2500 µg/L
• Liver biopsy marked haemosiderosis; LIC 37 mg/g dry
weight
• DNA sequencing revealed a 10 bp deletion followed by
9-bp insertion (maternal) and a Ala >Pro mutation at
position 477 (paternal chromosome)
• Treatment consisted of monthly plasma infusions 500 mL
+ bleeding. 10 years later, Hb 120g/L; ferritin: normal
Beutler E, et al. Blood. 2000;96:4071-4074.
Slide 8 of 21
Hypotransferrinaemia or Atransferrinaemia
Pathophysiology
• Atransferrinaemia results in reduced delivery of
iron to the erythroblasts and development of iron
deficiency anaemia (hypochromic–microcytic).
This triggers a massive but futile iron absorption
leading to iron overload outside of the erythron1
• Hereditary atransferrinaemia has been reported
in 7 families2
1.
2.
Andrews NC. Blood. 2008;112:219-230.
Beutler E, et al. Blood. 2000;96:4071-4074.
Slide 9 of 21
Deficiency of Ceruloplasmin
Case Presentation
• 56-year-old Italian man
• Hb 98 g/L; MCV 62.5 fl; MCHC 307 g/L
• Serum iron 2.96 µmol/L; ferritin 423 µg/L
• Ceruloplasmin 0.2 ng/mL
• Insulin-dependent diabetes mellitus since the age of 40
• CRP, fibrinogen: no evidence of inflammatory disease
• Liver biopsy showed iron overload
• DNA sequencing of CP gene: Gly >Arg at codon 631
(homozygous state)
Hb = haemoglobin; MCV = mean corpuscular volume; MCHC = mean corpuscular haemoglobin concentration;
CRP = C-reactive protein.
DiRaimondo D, et al. Intern Emerg Med. 2008 Apr 12. [Epub ahead of print] PMID: 18408989
Slide 10 of 21
Deficiency of Ceruloplasmin
• Ceruloplasmin (CP), a copper-containing ferroxidase, cooperates to
export iron with ferroportin 11
• CP deficiency results in low serum iron (= iron deficiency anaemia)
with concomitant deposition in the brain, liver, pancreas, basal
ganglia, and other organs1,2
• The constant feature of aceruloplasminaemia is a moderate degree
of anaemia, associated with low serum iron and high ferritin1
• Differential diagnosis1
– Anaemia of chronic diseases
– Wilson’s disease
– Hypotransferrinaemia or atransferrinaemia
• Treatment: chelation therapy; oral zinc sulfate3; no benefit from
phlebotomy1
1. DiRaimond D, et al. Intern Emerg Med. 2008 Apr 12. [Epub ahead of print] PMID: 18408989.
2. Miyajima H. Neuropathology. 2003;23:345-350. 3. Kuhn J et al. Brain Dev. 2007;29:450-453.
Slide 11 of 21
IRIDA (Iron-Refractory, Iron-Deficiency
Anaemia)
The Mask Mouse
“…a chronically iron-deficient mouse with an unusual
pattern of hair loss over the trunk but not the head (the
mask phenotype) due to a homozygous recessive genetic
mutation. Mask mice were shown to express inappropriately
high levels of hepcidin mRNA in the liver, even when fed an
iron-deficient diet. Using positional cloning techniques, Dr.
Beutler’s group was able to ascribe the mask phenotype to
a splicing error in the TMPRSS6 gene, which encodes a
membrane-bound serine protease.”1,2
1. Coghill JM, Ma A. Available at:
http://www.hematology.org/client_files/meeting/2007/newsdaily/HepcidinAdventureEarnsRaveReviewsatPlenary.pdf
2. Du X, et al. Science. 2008;320:1088-1092.
Slide 12 of 21
Mutation in TMPRSS6 (Matriptase-2),
Suppressor of Hepcidin Gene Expression, in
Familial Iron Deficiency Anaemia
Photograph: With permission from Du X. Science. 2008;320:1088-1092.
Graphic (top right): With permission from Ramsay AJ, et al. Front Biosci. 2008;13:569-579.
Graphic (bottom): With permission from Finberg KE, et al. Nat Genet. 2008;40:569-571.
Slide 13 of 21
IRIDA (Iron-Refractory, Iron-Deficiency
Anaemia)
Generation of mutant mice TMPRSS6-/- provided
evidence that matriptase-2 is an essential
regulator of iron homeostasis. In fact, in mice as
well as in humans, mutations in the TMPRSS6-/gene lead to severe iron deficiency anaemia.
This state is characterized by reduced
ferroportin expression (shown in the mice
model) and both animals and humans have high
hepcidin levels.
Folgueras AR, et al. Blood. 2008 Jun 3. [Epub ahead of print] PMID: 18523150.
Slide 14 of 21
IRIDA (Iron-Refractory, Iron-Deficiency
Anaemia)
Case-Reports
Patient 11
Patient 22
Patient
33
Patient
43
Patient
53
Patient
63
Patient 73
Patient 83
Patient 93
Age (y)
14
18
6
13mo.
17mo.
11
7
3
15mo.
Hb (g/L)
86
100
88
92
70
82
75
97
79
MCV (fL)
54.3
61
58
65
49
56
49
61
53
2.44
2.96
Ferritin (µg/L)
9
53
Transferrin
saturation (%)
6.52
sTfR
(mg/L)
5
2
10
5
3
4
4
2
70
133.5
IRON STATUS
Fe (µmol/L)
pHepcidin
(ng/mL)
1. Guillem F, Blood 2008 Jul 2. [Epub ahead of print] PMID: 18596229. 2. Melis MA, et al. Haematologica. 2008 Jul 4.
[Epub ahead of print] PMID: 18603562. 3. Finberg KE, et al. Nat Genet. 2008 May;40(5):569-71.
Slide 15 of 21
IRIDA (Iron-Refractory, Iron-Deficiency
Anaemia)
Case-Reports
Treatment
• Oral iron administration is ineffective
• Response to parenteral iron administration is
partial
• Anaemia becomes less severe in adulthood as a
consequence of the greater availability of the
limited amount of available iron to erythropoiesis
Melis MA, et al. Haematologica. 2008 Jul 4. [Epub ahead of print] PMID: 18603562.
Slide 16 of 21
Differential Diagnosis of Microcytic Anaemia
• Thalassaemia syndromes
• Certain haemoglobinopathies (Hb C)
• True (classical) iron deficiency secondary to
blood loss, iron-poor diet, increased iron needs,
Helicobacter pylori infection or gastric pathology
• Anaemia of chronic inflammatory diseases
• Certain forms of sideroblastic anaemia
• Genetic forms of iron deficiency anaemia
Slide 17 of 21
Diagnostic Approach—Genetic Forms of
Iron Deficiency Anaemia
• Look for consanguinity (recessive transmission)
• Is the anaemia associated with massive iron
accumulation? If yes, then do detailed
evaluation of CNS to distinguish between
aceruloplasmia (CNS damage present) and the
other forms with iron overload
• If presence of basophilic stippling and double
erythroid population in peripheral blood, then do
bone marrow aspiration to look for the presence
of ring sideroblasts
Slide 18 of 21
Diagnostic Approach—Genetic Form of Iron
Deficiency Anaemia
• Was the anaemia detected at birth or early in
life? If yes, then look for a mutation in the DMT1
or the TMPRSS6 gene
• Does the patient have microcytosis with high
serum iron values? If yes, then a DMT1 mutation
is highly suspected
• If no, then look for a TMPRSS6 mutation.
Hepcidin levels are also very helpful as hepcidin
is normal or increased in the TMPRSS6
mutation despite low serum iron
Slide 19 of 21
Main Biologic and Clinical Differences in
Genetic Forms of Iron Deficiency Anaemia
DMT1
Glutaredoxin 5
Atransferrinaemia
Aceruloplasminaemia
TMPRSS6
(matriptase-2)
At birth
Usually midlife
Late onset provided
some transferrin is
present
Late onset with
moderate
anaemia
18–24 mo
Liver iron overload
Yes
Yes
Yes
Yes
No
Brain damage
No
No
No
Yes
No
Serum iron
High
High
Low
Low
Low
Transferrin
saturation
High
High
High or nonmeasureable
Low
Low
Ringed
sideroblasts
No
Yes
No
No
No
Hepcidin levels
Low
Not yet
measured
Not yet measured
Not yet
measured
High for low iron
values
Low or normal
High
High
High
Normal
Age at diagnosis
Ferritin
Slide 20 of 21
Conclusions
• Iron deficiency anaemia is an acquired disease with an
estimated 3 billion people affected and represents a
major public health problem worldwide1
• Recent advances in iron metabolism led to the
recognition of new entities of iron deficiency anaemia in
nonbleeding and “high cost diet” nourished individuals
• Apparently rare, these genetic forms of iron deficiency
anaemia should be recognized by haematologists, as
they are refractory to classical oral or intravenous iron
administration
1. Andrews NC. Blood. 2008;112:219-230.
Slide 21 of 21